The present invention relates to a railroad lubricating composition and a method of lubricating the top of a rail.
In railroad lubrication, the top of a rail is lubricated to reduce lateral creep of a wheel which causes increased wheel flange-rail interaction. Wheel flange-rail interaction results in wear and additional fuel use and in the extreme is a contributing factor in derailment.
One of the benefits derived from a good top of the rail lubricant is that maximum safe speeds at which a train can run with worn equipment, termed Hunting speed, is increased. Increased train speed in a rail network can result in improved business operations such as meeting schedules and improved equipment utilization.
A top of the rail lubricant is applied after the locomotive has passed, providing lubrication for the rail car wheels. It is desirable that a top of the rail lubricant not persist on the rail after the train has passed. A persistent lubricant would reduce traction for the next locomotive passing on the track.
U.S. Pat. No. 5,492,642, which is hereby incorporated by reference, discloses a lubricant and a method for lubricating the top of a rail. The lubricant, however, does not perform well under moderate and extreme conditions of heat, i.e., when rail crown temperatures reach 130xc2x0 F. or higher. In particular, in actual field studies conducted during warmer months of the year, the lubricant was found to be insufficient for effective lubrication as it was consumed too quickly by the heat generated by the passage of a train over hot tracks. In fact, only ⅙th of the rail was adequately protected by the lubricant during the field studies. Certainly, the trailing cars in a train consist would not be adequately lubricated if a lubricant is consumed too quickly. Further, the assertion in U.S. Pat. No. 5,492,642 that xe2x80x9cthe lubricating composition is consumed in 5 to 15 minutes in the heat generated by a passing trainxe2x80x9d has proven to be inadequate in environments where the temperature is in excess of 75xc2x0 F. Also, the use of an alcohol in the composition of U.S. Pat. No. 5,492,642 has been found to accelerate the consumption of the lubricant too much for effective rail lubrication under moderate and extreme heat and is considered an unnecessary component of the composition.
Accordingly, it is one of the purposes of this invention, among others, to provide a top of the rail lubricant which is able to withstand greater ranges of temperature extremes in order to ensure satisfactory performance throughout the year. The lubricant must also be environmentally innocuous, ensure wheel and rail protection, decrease friction between a wheel and a rail, and reduce energy consumption needed to power a train consist over a wide range of temperatures.
It has now been discovered that this and other purposes can be achieved by the present invention which provides for a railroad lubricating composition and a method for lubricating the top of a rail. The lubricating composition is applied to the top of the rail in an amount sufficient to lubricate the wheel and rail interface and be consumed in the heat generated by the passage of one train. This aqueous lubricating composition represents an improvement over the composition described in U.S. Pat. No. 5,492,642 in that it will provide effective lubrication at temperatures ranging from 160 xc2x0 F down to xe2x88x9245xc2x0 F. and that alcohol is not necessary in the lubricating composition.
The lubricating composition of the present invention includes a synthetic lubricant, a synthetic thickener, a volatilizable solvent and a rust inhibitor.
The synthetic lubricant is a first polyoxyalkylene glycol including a linear copolymer of ethylene oxide and propylene oxide copolymer. The first polyoxyalkylene glycol has an average molecular weight of about 2,500. Further, the first polyoxyalkylene glycol is 25 to 45 wt % of the lubricating composition, preferably 30 to 40 wt % of the lubricating composition.
The synthetic thickener is a second polyoxyalkylene glycol including a linear copolymer of ethylene oxide and propylene oxide copolymer. The second polyoxyalkylene glycol has an average molecular weight of about 12,000. Further, the second polyoxyalkylene glycol is 0.5 to 3.0 wt % of the lubricating composition, preferably 1 to 2 wt % of the lubricating composition.
The volatilizable solvent is preferably propylene glycol. The solvent is 5 to 35 wt % of the lubricating composition, preferably 10 to 30 wt % of the lubricating composition.
Suitable rust inhibitors for the lubricating composition include phosphates, polyphosphates, sodium benzoate, quaternary amines, borax, amine borates, sodium borates, sodium molybdate, alkali metal nitrates, alkyl carboxylates, benzo tolyl triazoles, sulfonates, zinc salts, morpholine amines, ammonia, ethylenediamines, hydrazine, immadazolines, formamide, alkanolamines, carbonates, bicarbonates, sodium silicates, metasilicates, sodium chromates, calcium hydroxide, calcium bicarbonates, sodium nitrate and sodium chromate.
The lubricating composition is consumable, i.e., vaporizable. It evaporates in the heat and friction generated by the passage of the train over the rails.
The present invention also provides for a method of lubricating the top of a rail including applying a lubricating composition in an amount sufficient to wet the rail in the heat generated by the passing of a train. The lubricating composition applied in this method preferably includes a synthetic lubricant, a synthetic thickener, a volatilizable solvent and a rust inhibitor as described above.
The lubricating composition and method of the present invention relies on an aqueous mixture of the first and second polyoxyalkylene glycols.
The first polyoxyalkylene glycol is 25 to 45 wt %, preferably 30 to 40 wt %, of the lubricating composition. The content of the first polyoxyalkylene glycol in the lubricating composition is critical to the effectiveness of the lubricanting composition over a wide range of temperatures. Also, the first polyoxyalkylene glycol has an average molecular weight of about 2,500. A suitable first polyoxyalkylene glycol is a commercially available sample of Jeffox WL-1400, a functional fluid made by the Huntsman Corporation.
By including a higher content of the first polyxyalkylene glycol in the lubricating composition and a lower molecular weight first polyoxyalkylene glycol in comparison to the composition disclosed by U.S. Pat. No. 5,492,642, the top of the rail lubricating composition is effective in lubricating the rail under all extremes of temperature.
The second polyoxyalkylene glycol is 0.5 to 3.0 wt %, preferably 1 to 2 wt %, of the lubricating composition. Also, the second polyoxyalkylene glycol has an average molecular weight of about 12,000. A suitable second polyoxyalkylene glycol is UCON(copyright) 75-H-90000 which has an average molecular weight of approximately 10,300 and a viscosity of approximately 90,000 Saybolt Universal Seconds (SUS) at 100xc2x0 F. (37.8xc2x0 C.).
The lubricating composition also includes a volatilizable solvent which is propylene glycol. Propylene glycol is 5 to 35 wt %, preferably 10 to 35 wt %, of the lubricating composition.
The lubricating composition also includes a rust inhibitor. An example of a suitable rust inhibitor is Gateway ADDCO CP-105 brand which is a cathodic amine borate.
The lubricating composition does not include an alcohol as required in the composition of U.S. Pat. No. 5,492,642. In fact, the use of the alcohol in the composition of U.S. Pat. No. 5,492,642 has been found to accelerate the consumption of the lubricant too much for effective rail lubrication under moderate and extreme heat and is considered an unnecessary component of a lubricating composition.
The lubricating compositions of the present invention are formulated by methods well known in the art which can be carried out continuously. Some minor heat (100xc2x0 F.) may need to be added to a stainless steel kettle to accelerate the mixing of the viscous second polyoxyalkylene glycol thickener. Continuous stirring is recommended to maintain homogeneity as each individual component is added. Mixing of the final composition is recommended for 20 additional minutes once all components have been added.
The finished top of rail lubricating composition of the invention is designed to be filled into the tank of a locomotive mounted applicator, specifically the SENTRAEN 2000, and applicator developed by the Tranergy Corporation and detailed in U.S. Pat. No. 4,930,600. The composition is a consumable lubricant, which is the term used in the art for a lubricant that evaporates in the heat and friction generated by the passage of a train over the rails. Complete consumption of the top of rail lubricant allows for the next locomotive to pass over the rail without loss of traction or loss of the electric communication link through the rail (known as xe2x80x9cshuntingxe2x80x9d). The lead locomotive in a train is not lubricated, but the trailing cars are. The lubricator is mounted to the trailing locomotive.
U.S. Pat. No. 5,492,642 discloses that xe2x80x9cthe lubricating composition is consumed in 5 to 15 minutes in the heat generated by a passing trainxe2x80x9d. U.S. Pat. No. 5,492,642 also discloses that laboratory tests of top of the rail lubricants on the Illinois Institute of Technology (IIT) wheel rail simulation rig showing lubricant consumption in 5 to 15 minutes would correlate with field data. However, it has been shown by field studies that consumption rates of 5 to 15 minutes as predicted by the IIT wheel rail simulation rig are not adequate to ensure lubricity of a top of rail lubricant under moderate to extreme heat on the rail. To correlate well with data determined in the field, the top of rail lubricant must last at least 45-60 minutes with heat (of 130xc2x0 F. or higher) applied to the wheel and rail interface on the IIT wheel rail simulator rig during testing.
The following examples are provided to assist in further understanding the present invention. The particular materials and conditions employed are intended to be further illustrative of the invention and are not limiting upon the reasonable scope thereof.
Several top of the rail lubricating compositions were prepared and tested to illustrate features and advantages of the present invention.
In particular, the lubricating compositions were tested in a laboratory using the Illinois Institute of Technology (IIT) Wheel Rail Simulation rig. This test rig comprises a one twelfth ({fraction (1/12)}) scale wheel and rail for rail lubricating testing.